Thanks for your reply. I took a look at both things. The first thing I already looked at and followed all directions and AFAIC Firefox's pop-up blocker just doesn't work. Second, it looks like Ad Block Plus requires you to blacklist sites one at a time whose pop-ups you do not want to see. I don't want to get involved with black lists, white lists, etc. I just want to block ALL pop-ups. Microsoft apparently knows how to do it with its pop-up blocker in IE8 (I've never used IE9 so can't tell you about that) with the "High" setting. This setting blocks ALL pop-ups and doesn't interfere with other scripting. Surely something like this must be available for Firefox. Isn't there?